October 2006

This 2-week-old infant came into the office for an eruption that developed in the previous two days. Lesions were evident on the forehead and on the feet as seen in the photographs. He was the product of a full-term pregnancy and vaginal delivery without complications. He was eating well and had no fever.

Answer

The infant has neonatal lupus erythematosus.

This condition develops as a result of transplacental spread of maternal antibodies. The incidence of neonatal lupus erythematosus is between one in 2,500 to one in 20,000 births. Approximately 40% of the infants with the disease will have cutaneous findings, 40% will have cardiac findings, and 10-15% will have both cardiac and cutaneous findings. The antibodies most often seen are Anti-Ro (anti-SSA), Anti-La (anti-SSB), or Anti-RNP.

The skin lesions develop because of circulating antibodies and are generally similar to those observed in subacute cutaneous lupus erythematosus in older patients. The types of cutaneous findings may be 1) annular lesions; 2) discoid lupus lesions; 3) atrophic lesions; 4) “raccoon” eyes; or 5) telangiectasias.

The cardiac abnormalities develop because of maternal antibodies present at a gestational age of nine to 10 weeks. The antibodies selectively bind to the fetal myocytes and cells of the conduction system. Varying degrees of congenital heart block may be seen. If complete heart block (also known as third-degree) occurs, the resulting bradycardia is typically detected at the prenatal examination. These infants may require pacemakers in the neonatal period if the bradycardia is severe.

The differential diagnoses for the cutaneous lesions include hypersensitivity reaction or viral exanthem.

Infants who are diagnosed with neonatal lupus should have one ECG to evaluate for the presence of any lesser degree of heart block. Antibodies should be drawn from both mother and infant to confirm the diagnosis.

The cutaneous lesions may be triggered or worsened by sun exposure or UVA exposure.

They generally resolve by 6 to 12 months as the circulating antibody level decreases. The cutaneous lesions are treated with sun (particularly UVA) avoidance and protection. Topical hydrocortisone can be prescribed if there is significant inflammation.

For more information:

• Buyon JP, et al: Neonatal lupus: basic research and clinical perspectives. Rheum Dis Clin North Am 2005;31:299-313.
• Carder KR: Hypersensitivity reactions in neonates and infants. Dermatol Ther. 2005;18:160.
• Elish D, et al: Neonatal lupus erythematosus. Cutis 2006;77:82-86.
• Spence D, et al: Increased risk of complete congenital heart block in infants born to women with hypothyroidism and anti-Ro and/or anti-La antibodies. J Rheumatol. 2006;33:167-170.